we have a core switch 4507RE at the data center and 2 departments that connect to it via 10Gig fiber using X2-LRM modules.
Each department has a 3 switch stack and both locations are identical w.r.t type and setup scenario ..
the stack comprises of 1 x 3750E and 2 x 3750G . uplink is from X2 port tengig3/0/1 from the 3750E switch.
all of a sudden dept B started facing problem , where the ping would break and throughput comes around 6 - 7 mbps from that dept to the server behind the core switch. we also noted CRC error on both sides preodically ... so ....
we replaced the multimode fiber patch cords, re did the splicing , which stopped the CRC errors to appear.
now since morning the uplink port on the 3750E (3/0/1) would suddenly be in "down" state with (err-disabled) as the status when i run sh int ten 3/0/1
and i can also see CRC errors and input errors on the same interface.. if i do shut / no shut .. the port is up and active again.. but this has happned 3 times today..
the core swith side is still OK and no CRC / input / output errors are seen..
now on the 3750E i have swapped the 10gig module from 3/0/1 to 3/0/2 . the port is still up but i can see 400 CRC and 500 Input errrors.....
the module is also OK as i had replaced it with dept 1's module....
any anyone please suggest what and how to check ... im totally blank .. which side has the problem ..... how to trace it